We have been learning about BSE/mad cow in my AVS 437 Animal Diseases class this week. Does anyone know for sure how BSE started? Our teacher told us that the best guess is that cows were fed rendered animal feeds that contained sheep with scrapie and that the scrapie somehow developed into mad cow. Scrapie and mad cow are very similar but I am still curious...if this is the case why do we only see these type of diseases in sheep and cattle? Why not dairy goats? Is it because they weren't fed animal feeds? Are bison affected by BSE?